Features: Pro-Race – Forged piston developed with Vertex technology and race shape profile. All pistons are heat-treated with a T-5 hardening and tempering cycle . All piston skirts are coated with a high-tech Molybdenum Disulphite coating for faster break-in time and increased piston life . Forged pistons are forged from 2618 aluminum for superior strength and durability . Kits include piston, rings, wrist pin and circlips . Replacement two-stroke piston rings sold individually; four stroke piston rings sold as a set.